1. Field of the Invention
The present invention is a process to prepare pharmacologically active oxazolidinones and various intermediates used in the process.
2. Description of the Related Art
Various 5-acetamidomethyloxazolidinones are well known to those skilled in the art as pharmacologically useful antibactericals. Various methods are well known to those skilled in the art for preparing these useful therapeutic agents.
U.S. Pat. Nos. 5,164,510, 5,182,403 and 5,225,565 disclose 5'-indolinyloxazolidinones, 3-(5'-indazolyl)oxazolidinones, 3-(fused-ring substituted)phenyloxazolidinones respectively useful as antibacterial agents.
U.S. Pat. Nos. 5,231,188 and 5,247,090 disclose various tricyclic [6.5.5] and [6.6.5]-fused ring oxazolidinones useful as antibacterial agents.
International Publication WO93/09103 discloses mono- and di-halo phenyl oxazolidinone anti-bacterials which are useful as pharmaceutical agents for their anti-bacterial action.
Prior art processes to make oxazolidinones involve condensation of an aromatic carbamate with a non-nitrogen containing three-carbon reagent to give an intermediate oxazolidinone with a hydroxymethyl substituent at the 5-position. The hydroxyl must then be replaced by an acetamido group to give the pharmacologically active 5-acetamidomethyloxazolidinones. Many variants of this essentially two-step process have been developed.
U.S. Pat. Nos. 4,150,029, 4,250,318, 4,476,136, 4,340,606 and 4,461,773 disclose the synthesis of 5-hydroxymethyloxazolidinones from amines (R-NHX.sub.1, where X.sub.1 is --H or p-toluenesulfonyl) and R,S-glycidol (C.sup.# H.sub.2 --O--C.sup.# H--CH.sub.2 --OH where the carbon atoms marked.sup.# are bonded together, cyclized to form an epoxide). The mixture of enantiomers produced by this process (represented by the formula R--NH--CH.sub.2 --CHOH--CH.sub.2 --OH) are separated by fractional crystallization of the mandelic acid salts. The enantiomerically pure R-diol is then converted into the corresponding 5R-hydroxymethyl substituted oxazolidinones by condensation with diethylcarbonate in the presence of sodium methoxide. These 5R-hydroxymethyl substituted oxazolidinones must be aminated in a subsequent step.
J. Med. Chem., 32, 1673 (1989), Tetrahedron 45, 1323 (1989) and U.S. Pat. No. 4,948,801 disclose a method of producing oxazolidinones which comprises reacting an isocyanate (R--N.dbd.C.dbd.O) with (R)-glycidyl butyrate in the presence of a catalytic amount of lithium bromide--tributylphosphine oxide complex to produce the corresponding 5R-butyryloxymethyl substituted oxazolidinone. The process is performed at 135-145.degree.. The butyrate ester is then hydrolyzed in a subsequent step to give the corresponding 5R-hydroxymethyl substituted oxazolidinone. The 5R-hydroxymethyl substituted oxazolidinone must then be aminated in a subsequent step.
Abstracts of Papers, 206th National Meeting of the American Chemical Society, Chicago, Ill., August, 1993; American Chemical Society: Washington, D.C., 1993; ORGN 089; J. Med. Chem. 39, 673 (1996); J. Med. Chem. 39, 680 (1996); International Publications WO93/09103, WO93/09103, WO95/07271 and WO93/23384; PCT applications PCT/US95/12751 and PCT/US95/10992; Abstracts of Papers, 35th Interscience Conference on Antimicrobial Agents and Chemotherapy, San Francisco, Calif., September, 1995; American Society for Microbiology: Washington, D.C., 1995; Abstract No. F208; Abstracts of Papers, 35th Interscience Conference on Antimicrobial Agents and Chemotherapy, San Francisco, Calif., September, 1995; American Society for Microbiology: Washington, D.C., 1995; Abstract No. F207; Abstracts of Papers, 35th Interscience Conference on Antimicrobial Agents and Chemotherapy, San Francisco, Calif., September, 1995; American Society for Microbiology: Washington, D.C., 1995; Abstract No. F206; Abstracts of Papers, 35th Interscience Conference on Antimicrobial Agents and Chemotherapy, San Francisco, Calif., September, 1995; American Society for Microbiology: Washington, D.C., 1995; Abstract No. F227; disclose the reaction of a carbamate with n-butyllithium, lithium diisopropylamide or lithium hexamethyldisilazide at -78.degree. to -40.degree. followed by glycidyl butyrate at -78.degree. followed by warming to 20-25.degree. to produce 5R-hydroxymethyl substituted oxazolidinones where the ester is cleaved during the reaction. The 5R-hydroxymethyl substituted oxazolidinones must then be aminated in a subsequent step.
International Publication WO95/07271 discloses the ammonolysis of 5R-methylsulfonyloxymethyl substituted oxazolidinones.
U.S. Pat. No. 4,476,136 discloses a method of transforming 5-hydroxymethyl substituted oxazolidinones to the corresponding 5(S)-aminomethyl substituted oxazolidinones (VII) that involves treatment with methane sulfonyl chloride followed by potassium phthalimide followed by hydrazine.
J. Med. Chem., 32, 1673 (1989) and Tetrahedron 45, 1323 (1989) disclose a method for transforming 5-hydroxymethylsubstituted oxazolidinones into the corresponding 5S-acetamidomethyl substituted oxazolidinones that involves treatment with methanesulfonyl chloride or tosyl chloride, followed by sodium azide, followed by trimethylphosphite or platinum dioxide/hydrogen, followed by acetic anhydride or acetyl chloride to give the desired 5(S)-acetamidomethyl substituted oxazolidinone.
U.S. provisional application Ser. No. 60/015,499 discloses a process to prepare 5(S)-hydroxymethyl substitued oxazolidinone intermediates which are useful in the preparation of the pharmacologically active 5(S)-acetamidomethyloxazolidinoes. It futher discloses a process to convert the 5-hydroxymethyl substitued oxazolidinone intermediates into 5-aminomethyl substitued oxazolidinone intermediates which can be acylated to produce the pharmacologically active 5(S)-acetamidomethyl substitued oxazolidinones.
J. Med. Chem., 33, 2569 (1990) discloses the condensation of an isocyanate with racemic glycidyl azide to produce a racemic 5-azidomethyl-substituted oxazolidinone. Two subsequent steps are required to convert the racemic azidomethyl-substituted oxazolidinone into racemic 5-acetamidomethyl-substituted oxazolidinone, which has antibiotic activity. The present invention converts isocyanates into the (S)-enantiomer of acetamidomethyl-substituted oxazolidinones which have greater antibiotic activity than the racemates, in one step.
U.S. Pat. No. 5,332,754 discloses (col. 2, lines 14-34) that racemic oxazolidinone-CH.sub.2 --NH--Ac can be synthesized in one step by condensation of a carbamate with racemic glycidyl acetamide "in the presence of a base" such as an amine, "alkali metal hydroxide, an alkali metal alkoxide, and the like", and that "it is preferred to carry out the reaction under heating . . . preferably at a temperature between 90.degree. C. and 110.degree. C" (col. 4, lines 44-56). Evidence indicates that under these conditions rearrangement to an undesired product occurs. The patent provides no yields or description of this process in the Examples. Indeed, the EXAMPLEs disclose not a one-step process but multi-step routes that are known to those skilled in the art involving mesylation of a 5-hydroxymethyl substituted oxazolidinone followed by azide displacement, hydrogenation and acetylation of the amine. In particular, see EXAMPLEs 59-63. The present invention differs in that the contacting between the carbamate (IX) and the epoxide (VIIIB) is performed under conditions that competing rearrangement to the undesired side products is largely suppressed.
Tetrahedron Letters, 37, 7937-40 (1996) discloses a sequence for synthesis of S-glycidylacetamide (R.sup.2 =--NHAc) and a process for condensation of a carbamate with 1.1 equivalents of n-butyl lithium (THF, -780) followed by 2 equivalents of S-glycidylacetamide to give the corresponding 5S-acetamidomethyl-substituted oxazolidinone. The present invention differs in that the contacting between the carbamate (IX) and S-glydidylacetamide is performed in the presence of lithium alkoxide bases or the carbamate (IX) is contacted with the S-chlorohydrin acetamide (VIIIA) or S-chloroacetate acetamide (VIIIC) or an isocyanate (XI) is contacted with the S-chlorohydrin acetamide (VIIIA).
U.S. Pat. No. 3,654,298 discloses the synthesis of 5-alkoxymethyl-3-aryl-substituted oxazolidinones by sodium ethoxide induced cyclization of chlorocarbamates. The present invention differs in that the substituent at the 5-position is acylamino.